Organic and inorganic light active devices and methods for making the same

Abstract

A light active device includes a semiconductor particulate dispersed within a carrier material. A first contact layer is provided so on application of an electric field charge carriers having a polarity are injected into the semiconductor particulate through the carrier material. A second contact layer is provided so on application of the electric field to the second contact layer charge carriers having an opposite polarity are injected into the semiconductor particulate through the carrier material. The semiconductor particulate comprises at least one of an organic and an inorganic semiconductor. The semiconductor particulate may comprise an organic light active particulate. When constructed as a light emitting device, an electric field applied to the semiconductor particulate through the carrier causes charge carriers of opposite polarity to be injected into the semiconductor particulate. The charge carriers combine to form carrier pairs which decay and give off light.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This is a utility application of provisional application Ser. No. 60 / 469,667, filed May 12, 2003, and is a continuation-in-part of U.S. Utility patent application Ser. No. 10 / 375,161, filed Feb. 26, 2003, which is a continuation-in-part of U.S. Utility patent application Ser. No. 10 / 321,161, filed Dec. 17, 2002 which is the US Utility Patent Application of a Provisional Patent Application Ser. No. 60 / 427,333, filed Nov. 19, 2002.BACKGROUND OF THE INVENTION [0002] The present invention pertains to organic and inorganic light active devices, and hybrids thereof, and methods of making the same. More particularly, the present invention pertains to devices and methods for fabricating light active devices that can be used for applications such as general lighting, display backlighting, video displays, Internet appliances, electronic books, digital newspapers and maps, stereoscopic vision aides, head mounted displays, advanced vehicle windshie...

AI Technical Summary

Benefits of technology

[0028] It is an object of the present invention to overcome the drawbacks of the prior art. It is an object of the present invention to provide a method of fabricating a light active device by dispersing three dimensionally a semiconductor particulate within a carrier material. The resulting structure has individual point sources of light emission dispersed within a protective barrier material. The barrier material provides strength to the device and adhesion to the electrodes and / or other films and prevents contamination of the semiconductor particulate. The inventive fabrication method also allows multiple colors to be emitted from the inventive mixture between a single pair of electrodes forming a pixel or device. In an inventive display driving scheme, an array of such pixels is driven so that bursts of color emissions occur in rapid succession resulting in the perception by the human eye of a range of colors in the visible spectrum. Thus, in accordance with this aspect of the invention, a single emissive layer and pair of electrodes can be used to create a full color video display. The inventive Organic Light Active Material (OLAM™) structure can also be used to detect a spectrum of colors when the device is constructed as a photodetector.

Problems solved by technology

Further, the absorption of light by the semiconductive polymer results in positive and negative charges that produce an electric current.

The unstoppable march of technology often changes the way we see the world.

One of the biggest challenges to the OLED display industry is from contamination by water and oxygen.

The materials involved in small molecule and polymer OLEDs are vulnerable to contamination by oxygen and water vapor, which can trigger early failure.

This issue is exacerbated when non-glass substrates are used.

Neither of these solutions is adequate, adding to the cost and complexity of forming an OLED device.

In the end, the problems caused by the ingress of water and oxygen to the organic stack continue to pose serious technical issues. FIG. 111 illustrates a prior art OLED device.

Such thin layers of organic material are susceptible to major problems, such as loss of film integrity, particularly when applied to a flexible substrate. FIG. 112 illustrates a prior art OLED device wherein a dust spec creates an electrical short between the electrodes.

The extreme thinness of the layers of organic material between conductors also results in electrical shorts easily forming due to even very small specks of dust or other contaminants.

Because of this limitation, costly cleanroom facilities must be built and maintained using the conventional OLED thin film fabrication techniques.

However, there are some serious disadvantages to the adapting of inkjet printing to OLED display fabrication.

Inkjet printing does not adequately overcome the problem of material degradation by oxygen and water vapor. FIG. 113 illustrates a prior art OLED device wherein the thin organic film stack is degraded by the ingress of oxygen and / or water.

Elaborate and expensive materials and fabrication processes are still required to provide adequate encapsulation to protect and preserve the thin organic films.

It is difficult to align display pixel-sized electrodes and inkjet printed OLED material with the accuracy needed to effect a high resolution display.

However, there are still some technical hurdles that remain to be solved before OLED displays will realize their commercial potential.

One of the biggest challenges to the OLED display industry is from contamination by water and oxygen.

The materials involved in small molecule and polymer OLEDs are vulnerable to contamination by oxygen and water vapor, which can trigger early failure.

It is generally very difficult to form the electrodes with the precise alignment needed for forming a pixilated display.

This task is made even more difficult in a multicolor display, where the OLED pixels emitting, for example, red, green and blue, are formed side-by-side to fabricate a full color display.

However, the electrode alignment issue still poses a problem.

Aligning the shadow masks is difficult, and requires extreme precision.

However, there are some serious disadvantages to the adapting of inkjet printing to OLED display fabrication.

It is still difficult to lay down precise layers of material using the spray heads of inkjet printers.

Inkjet printing does not adequately overcome the problem of material degradation by oxygen and water vapor.

Elaborate and expensive materials and fabrication processes are needed to provide adequate encapsulation of the display elements to prevent early degradation of the OLED material due to water and oxygen ingress.

It is difficult to align display pixel-sized electrodes and inkjet printed OLED material with the accuracy needed to effect a high resolution display.

Electrical shorts and the destruction of pixels result from the inclusion of even miniscule foreign particles when forming the organic thin film layers.

To limit this serious drawback, the conventional fabrication processes requires the use of expensive clean room or vacuum manufacturing facilities.

These thin films must also be deposited very uniformly and precisely, which has proven extremely difficult to do.

These thin layers of organic material are susceptible to major problems, such as shortened device lifetime due to ingress of water and oxygen, and delamination, particularly when applied to a flexible substrate.

The extreme thinness of the layers of organic material between conductors also results in electrical shorts easily forming due to even very small specks of dust or other contaminants.

Because of this limitation, costly cleanroom facilities must be built and maintained using the conventional OLED thin film fabrication techniques.

Organic light emitting devices offer tremendous potential due to the inherent qualities of the organic materials, however, the current state of the art fabrication methods are limiting the delivery of this potential to the consumer.

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